>> reporter: the first thought, because of norway's involvement in afghanistan, nato in libya, perhaps this was al qaeda or a libyan reaction, but it turns out to be a lone norwegian, who was arrested, believed to be involved in the bombing and the shooting. said to be in his 30s, a military veteran who has grievances with the government and now talking to police, a kind of norway version of timothy mcveigh, the american military vet who blew up thehe federal building in oklahoma city in the '90s. >> so, what do you know about the bomb itself? >> reporter: well, the bomb went off. it is not as high explosives as they thought. a homemade bomb. they also found several other undetonated bombs on that island at the youth camp, which he had taken with him. >> we're looking at the debris right now. that shattered glass. and we all began thinking about buildings here in this country today and that video of the practice run with the barriers we set up in front of so many buildings across this country. >> reporter: well, the u.s. has been very vigilant in protecting government buildings. it pro